The present invention relates generally to rectilinear motion proportional solenoids and, more particularly, to such solenoids which produce an output force which is linearly proportional to the applied electric current input.
Specifically, the present invention provides a novel embodiment and improvement upon the invention disclosed in U.S. Pat. No. 4,463,332 which issued July 31, 1984 to the same inventor and assignee as the present invention. The complete disclosure and specification of that patent are incorporated herein by reference.
Further objects of the present invention include providing a proportional solenoid having decreased flux leakage out of the magnetic circuit.
Another object is to provide a proportional solenoid having higher magnetic permeance and a decreased housing size without loss of output force.
Still another object is the provision of a more efficient proportional solenoid of simplified construction.
These and other objects of the present invention are attained by the provision of a solenoid device having a permanent magnet mounted directly on the polepiece at the core gap to provide an initial magnetic flux through the polepiece and to focus the induced magnetic flux additionally supplied upon actuation of the solenoid. The magnetic flux through the polepiece continues across the core gap and into an armature which is supported by linear rate springs and spaced from the housing by side gaps. A coil device is mounted about the polepiece to provide induced magnetic flux in response to the applied electrical current input. The polepiece is adjustable within the housing to establish various core gap distances. The side and core gap dimensions within the magnetic flux circuit are proportioned relative to each other to maintain constant magnetic permeance about the circuit during soleoid actuation.
Other objects, advantages and novel features of the present invention will become readily apparent upon consideration of the following detailed description in conjunction with the drawings.